Bulk loading refuse disposal vehicles are well known. Such refuse vehicles have a front end loading device for lifting a bulk container, and have a hopper mounted on the vehicle body for receiving the contents of the container. At the rear end of the hopper there is a door which can be released to dump the contents at a dump.
Within the hopper there is a ram, which is adapted to pack and compress the contents towards the rear of the hopper.
Typically these refuse vehicles are operated by private owners, who undertake collection of refuse, typically at commercial sites, for a contract price.
Usually the dump site will be at some distance from the locations where refuse will be picked up. Consequently, a large part of the driver's time will be occupied in driving to and from the dump site, and dumping the contents.
Clearly, therefore, it is advantageous from the viewpoint of economy of operation if the hopper can carry the largest possible payload. In this way the driver will be able to serve a larger number of customers, before being obliged to drive to the dump site and unload.
Various factors affect the size of the payload.
The overall volume of the hopper is a prime consideration. Clearly, there are dimensional limits on the height and width to which the hopper can be constructed. The only practical way in which the hopper can be increased in volume is by increasing its length. However, there are also practical limits on the length of the hopper. In the majority of cases the rams for compacting the contents are operated by means of hydraulic cylinders. In some cases the ram is used to eject the contents at the dump site. In other cases a form of tipping action is provided, and separate hydraulic cylinders are installed which tip the body so that the contents slide out of its own weight. If a tipping body is adopted, then it is impractical to extend the length of the body to any extent, since the longer the body the more difficult it becomes to tip. On the other hand, if the compacting ram itself is used for ejecting the contents, then the length of the cylinders operating the ram impose limitations on the length of the body. Multi-cylinder telescopic cylinders have been proposed for operating the ram, but they are not always as reliable as simple cylinders. In addition, they tend to require more power for their operation, and consequently consume more fuel, due to the greater volume of the larger diameter cylinders in a set of telescopic cylinders. They are also somewhat slower to operate, than simple cylinders. A further fact which affects the total payload that can be packed in any given container is the force used in compacting. Clearly, the greater the force that can be applied to the payload, the more its volume will be reduced and the greater the payload will be, within the same space.